This invention provides a low cost means for achieving affordable solar energy by greatly reducing the cost of solar concentrators which increase (concentrate) the density of solar energy incident on the solar energy converter. A limiting factor in the utilization of solar energy is the high cost of energy converters such as photovoltaic cells. For example, for the purpose of generating electricity, a large area of expensive solar cells may be replaced by a small area of high-grade photovoltaic solar cells operating in conjunction with the inexpensive intelligent micro-optics of this invention. Thus the instant invention can contribute to the goal of achieving environmentally clean energy on a large enough scale to be competitive with conventional energy sources.
The 1979 Gyricon U.S. Pat. No. 4,143,103 of Sheridon, entitled “Method of Making a Twisting Ball Display” and the 2002 U.S. Pat. No. 6,441,946 of Sheridon, entitled “Swollen Gyricon Displays and Method of Making Same” are exclusively concerned with Displays. There appears to be no mention of any other application than Displays, either specifically or by general statement. In these Sheridon patents, no mention is made of a mirror in the gyricon balls, nor is there any mention of specular reflection as would be obtained from a mirror. On the contrary, diffuse reflection needs to be increased from the balls so the Gyricon display may easily be observed from all angles. Certainly there is no anticipation of a solar concentrator application, solar propulsion assist, optical switching or any other micro-mirror application. Furthermore, a uniform monolayer(s) of micro-mirrored balls are preferred in these applications, whereas the Sheridon patents only teach a random dispersion of non-mirrored Gyricon balls.
The instant invention is primarily concerned with the manufacture of sheets that hold solar concentrator micro-mirrors for nearly frictionless rotation. However, it has broader applications wherever mirrors are used for micro-mirror focusing applications such as for solar propulsion assist and optical switching.
Definitions
“Binder” refers herein to a material additive that is used to promote solidification, provide mechanical strength, or to ensure uniform consistency.
“Concentrator” as used herein in general is a micro-mirror system for focusing and reflecting light. In a solar energy context, it is that part of a Solar Collector system that directs and concentrates solar radiation onto a solar Receiver.
“Dielectric” refers to an insulating material in which an electric field can be sustained with a minimum power dissipation.
“Elastomer” is a material such as synthetic rubber or plastic, which at ordinary temperatures can be stretched substantially under low stress, and upon immediate release of the stress, will return with force to approximately its original length. Silicone elastomers have exceptional ability to withstand ultraviolet light degradation.
“Electret” refers to a solid dielectric possessing persistent electric polarization, by virtue of a long time constant for decay of charge separation.
“Focusing planar mirror” is a thin almost planar mirror constructed with stepped varying angles so as to have the optical properties of a much thicker concave (or convex) mirror. It can heuristically be thought of somewhat as the projection of thin equi-angular segments of small portions of a thick mirror upon a planar surface. It is a focusing planar reflecting surface much like a planar Fresnel lens is a focusing transmitting surface. If a shiny metal coating is placed on a Fresnel lens it can act as a Fresnel reflector.
“Packing fraction” herein refers to the fraction of an available area occupied by the collection (ensemble) of rotatable elements.
“Plasticizer” as used herein refers specifically to a dielectric plasticizer fluid that is absorbed by an elastomer thereby causing it to swell thus creating a spherical shell around each of the micro-mirror balls which do not substantially absorb the plasticizer. More commonly plastizers are added to a material to make it softer, more flexible, or more moldable.
“Receiver” as used herein in general is a system for receiving reflected light. In a solar energy context, it receives concentrated solar radiation from the micro-mirror assembly for the conversion of solar energy into more conveniently usable energy such as electricity.
“Silicone” as used herein refers to a heat-stable, rubber-like elastomer that is a water repellent, semiorganic polymer of organic radicals attached to silicon containing molecules, such as dimethyl silicone. Silicone elastomers are an excellent material within which to embed the mirrored balls or cylinders, because of their durability with respect to ultraviolet light, among other reasons.
“Thermoplastic” refers to materials with a molecular structure that will soften when heated and harden when cooled. This includes materials such as vinyls, nylons, elastomers, fuorocarbons, polyethylenes, styrene, acrylics, cellulosics, etc.
“Zeolyte” is a group of hydrous tectosilicate minerals such as analcime, chabazite, natrolite, and stilbite usually characterized by an aluminosilicate tetrahedral framework and ion-exchangeable large cations permitting reversible dehydration. Zeolytes are an excellent material to add to the plastizer liquid to help keep it clean and if necessary deionized.